x32: Fix alignment fail in struct compat_siginfo

Adding struct _sigchld_x32 caused a misalignment cascade in struct
siginfo, because union _sifields is located on an 4-byte boundary
(8-byte misaligned.)

Adding new fields that are 8-byte aligned caused the intermediate
structures to also be aligned to 8 bytes, thereby adding padding in
unexpected places.

Thus, change s64 to compat_s64 here, which makes it "misaligned on
paper".  In reality these fields *are* actually aligned (there are 3
preceeding ints outside the union and 3 inside struct _sigchld_x32),
but because of the intervening union and struct it is not possible for
gcc to avoid padding without breaking the ABI.
Reported-and-tested-by: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1329696488-16970-1-git-send-email-hpa@zytor.com

arch/x86/include/asm/ia32.h

@@ -130,8 +130,8 @@ typedef struct compat_siginfo {
 			unsigned int _pid;	/* which child */
 			unsigned int _uid;	/* sender's uid */
 			int _status;		/* exit code */
-			s64 _utime;
-			s64 _stime;
+			compat_s64 _utime;
+			compat_s64 _stime;
 		} _sigchld_x32;
 
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */